<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #dv{
            width: 80%;
            height: 900px;
            background: goldenrod;
            display: none;
        }
    </style>
</head>
<body>
    <button onclick="btnshow()">弹出成</button>
    <div id="dv">
         <div id="dvv"><span id="x" onclick="dvvxx()">x</span></div>
    </div>
    <script>
        var btn=document.getElementsByTagName('button')
        var dvv=document.getElementById('dv')
        var dvvx=document.getElementById('x')
         function btnshow() {
            dvv.style.display='block'
         }
         function dvvxx() {
            dvv.style.display='none'
         }
    </script>
</body>
</html>